conner



C. W. CONNEH. METHOD OF PRODUCING BIFOCAL LENSES.

, APPLICATION FILED MAY 2, 19.19. 23, 1920. 14,822.

a SHEETS-SHEET I.

Reisgued Mar.

INVENTOR 61142455 M Cow/v55:

ATTORNEY:

C. W. BONNER. METHOD OF PRODUCING BIFOCAL LENSES.

APPLICATION FILED MAY 2| 1919.

Beissued Mar. 23, 1920.

E. .E R mm W6 a a M 6,

BY v

Y ATTORNEYS I c. w. CONNER.

- METHOD OF PRODUCING BIEOCAL LENSES. I APPLICATION FILED MAY2,1919. Relssued Mar. 23, 1920.

. 14,822 41' 4o FIEI' 5 I I INVENTOR. C/meu's M Cow/v52 haw A TTORNEYS j vented a new and'useful 8Q.cave surface and an .a vertical section of PATENT OFFICE.

UNITED STATES cilmns w. comma, or

WIL MINGTON, NORTH CAROLINA, ASSIG-NOR T ON EPIECE v METHOD or r'aonucme iarrocan LENSES.

14,822. 1 I v onm rxb. 925,802, dated June 22, 1909, 'Serial No. 1 .filed May 2, 1819.

To all whom it may concern:

Be it .known that I, CHARLES W. CONNER, a citizen of the United States, residin at ilmington, in the county of New anover and State of North Carolina, have in- Method of Producing Bifocal Lenses, of'which the followingi is a specification.

' he ob ect of my invention is to produce by successive steps from a single piece of crystal a lens which shall have upon one face a pair of surfaces of di'flerent diop- .trics, said surfaces being produced either simultaneously or in succession, as hereinafter described. i

In order that my process may be thoroughly understooch the accompanying draw ings i lustrate apparatus by means of which e process may be performed, and also illustrate several forms of the result of my process.

Figure 1 is an elevationcf one form of :my improved rinding wheel togetherjwith an apparatus or using a plan thereof.

the'same. Fig.2 is Fig. 3 i

is a vertical section of' the apparatus .for finlshing one of the surfaces. Fig. 4 is a plan thereof. Fig. 5 is a View showin a transverse section of a crystal provided on one face with a coninternal plain surface; an eye glass lens cut I from the crystal; a similar section thereof I elevation of a I section finished on .verse section provided on finished on the opposite side; and a partial elevation of a grinding element forproduci'ng the crystal. Fig. 6 is a view showin a transverse section of a crystal provided with a concave surface of one dioptrio and an internal surface of a different -dioptric; a vertical section lens out from the crystal; finished on the op of an eye glass posite side; and a partial rmding element for producing the crystaf Fig. 7 is a transverse section of a crystal provided on one face with a concave portion and an intermediate con vex portion; a vertical section of an eye glass lens cut from the crystal; a similar the opposite side; and a partial elevation ,of a grinding element for producing the crystal. Fig. 8 is a trans one face with a v convex portion and an intermediate plain portion; a vertical section 9f a, lens cut from'* a similar section l Specification of Reissueg Letters Patent. Reissued Dial. 23, 1920.

153,697, filed April-21, 1903. 7 Application for reissue Serial No. 294,280.

an eye glass lens cut from the crystal;

similar section finished on the side; and a partial elevation of a grinding element for producing the crystal. Fig. 10 is a diagram of the leiissliown in Fig. 6.

Fig. 11 1s anelevation of a grinding wheel in which the intermediate portion is suiliciently depressed so that it'willnot serve as a grinding surface.

In Figs. 1 to at inclusive, 15 indicates a grinding wheel, the intermediate periph eral portion 16 of which is parallel with the axis of rotation while'the edge portions 17, 17 are convex. WVheel 15 is mounted upon the arbor l8 and rotated by means of a pulleyl9. Mountedabove wheel 15, pref erably but not necessarily, to arbor 18-, is a lens rotating arbor 20 journaled in a suitable bracket 21 which is adjustable along a line substantially parallel with the axis of arbor 18 by any suitable means such as an adjusting screw bor 20 is rotated, preferably at a considerably higher speed than arbor 18 by means of a pulley 28 and belt 24 which belt passes around idlers 25 and a driving wheel 26 carriedby arbor l8. Arbor 20 is capable of vertical. movement within its bearing bracket 21 toward and from the periphery ofthe grinding wheel 15 and is normally forced downward by a spring 27. The ar-. I her 20 is preferably held in its upper position by means of a sleeve mounted withbearing of bracket 21\and provided pin28 projecting through a bayonet In operation the lower end adapted ing head 30 to which crystal 31 is attached in the usual manner. The crystal 31 may preferably be roughed out, so as to partially conform Wit the curvature of the grinding surfaces 17, by the ordinary grinding means whichneed the head 30 together tal 31 has b held in engagement with the periphery of arbor 20 is with its. attached ci to engage and rotate the lens holdopposite not be here described. After the grinding wheel 15 by spring 27 and the dioptric of the intermediate surface 43. This parts then rotated, the grinding wheel upon Wheel will produce the lens shown with a its arbor 1'8, and the crystal 31 upon the minus central surface 43 and asurrounding axis of arbor 20. The grinding surface 16 minus surface 42 of smaller dioptric. The 5 operates to produce a central ens surface lens after being finished on the opposite side 70 concentric with the arbor 20 and the grindis also shown. ing surfaces 17, 17 simultaneously operate In Fig. 7 the grindin surfaces 44:, 44 are to produce a lens surface concentric with plus, while the inter-me iate surface i5 is a arbor 20 and surrounding the lens surface minus dioptric andconsequentlythe lens proproduced by the grinding surface 16. duced has a central plus surface 6L5 and a 75- If desired, the two lens surfaces may be surrounding ininus'surface H. The lens ground and finished by the same or similar aft r beih fi i h d n the opposite side is wheels, but in practice, I find that this may also Show I I result in an imperfect central lens surface In Fig. 8 the minus grindingsurfaeesvlfl, for the reason that slight irregularities in 46 have a plain surface 47 interposed find 80 the surface 16, especially in a line directly this will produce a lens having a central flat beneath or very closely beneath the axis of circular portion 4.7 and a surrounding plus; arbor 20, may possibly produce conc ntri surface 46'; The lens after being finished ridges and hollows in the lens surface. For on the opposite sideis also shown. that reason after the crystal 31 has been In Fig. 9 the grinding surfaces is, 48 are 85 roughed out by the wheel such as shown 111 minus and the intermediate grinding sur- Fig. 1, where the surfaces 15 and 1'7, 17 a e face 49 minus of a greater dioptric thus prosubstantially .the proper dioptrics for the ducing. a lens having an intermediate plus WVO dBSllBd surfaces, I remove Sttltl \VllQGl Surface 49', angl a surrounding plus surfacg and. substitute therefor a wheel such as 48. The lens after being finished on the' '90 that shown in Fig. 11 where the intermeopposite side is also shown. Q diate grinding surface is removed, as at 7), In Fig. 10 I have shown a section of the and grinding is continued until a slight eye glass lens illustrated in Fig. 6 and have surplus of material is left in the center further shown that the short radius a is -of the crystal, as shown in Fig. 3. lhe common to both of the lens surfaces 25L95- external surface is finished with a wheel and l3 similar to the wheel shown in Fig. 11, It will be readily understood that, if do: or by any other desired means, and the sired. one of the grinding surfaces 17, crystal is then transferred to the rotating may be omitted, or if desired. a single grindheadg32 shown 'inFig. 3, and there rotated ing surface ()1 set with relation to the arbor' 100 in conjunction with a grinding plate 33, the 20 may be used for producing the 'exterrml under face of which has been given the or surrounding lens surface, but both of proper dioptric curve desired for the central these changes would probably prove to ,be surface and the surplus material of the cenobjectionable for the reason that in that case 40 for of the crystal is then reduced by this the head 30 would have to be rigidly congrinder until the line of junction between nected with the arbor 20 and there would the central surface and the surrounding surnot be that flexibility of grinding action face is made practically invisible. "The which appears to be essentialfor the produc-' grinding plate 33 is of less diameter than tion of an accurate lens. p i 45 the lens surface which it is to grind and After the large lens, being the firstilens finish, so that, as it is moved transversely of illustrated in Figs. 5, 6, 7 8 and 9, has been the crystal across its center by the arm 3 1, provided on one face with two bifocal surit will be rotated upon the pin as an axis, faces, one surrounding the other, it is reby reason'of the rotation of the crystal Si by .duced to substantially the size of an e e 50 head 32. V glass'or spectacle lens, as shown in t e In Fig. 5 I have shown a portion of the small lens illustrated in Figs. 5 to by cutperiphery of a grinding wheel having a air ting or removing a portion of the lens so of separated surfaces 40, &0 which are c the that the smaller surface will lie at the lower same dioptric and an intermediate grinding edge of the finished lens. It is thus possible 55 surface 41 which is arallcl with the axis of. to produce from a single crystal a bifocal rotation. Such a w eel will produce a lens lens with the near vision port-ion properlysuch as shown --,in Fig. 5 with a' fiat central positioned at the lower edge.

circular surface 41. The finished eye glass After saidsmall-iens, shown in Figs. 5 to lens is also shown in the same figure, a por- 9, which is approximately the size of an eye ,330 tion of the crystal having been removed so glass or spectacle lens, has been thus formed, as to bring the surface 41 to one edge of the the side of the crystal opposite the side upon finished "lens. The lens after being finished which the two surfaces of different dioptrics onthe opposite side is also shown. have been formed, is given the desired dilnjEigfjfi the surfaces 42, 42 erect a plus optric conformation to complete the lens, as 65 dioptric h'ch is greater than the plus 'illustrated in Figs; 5 to 9. This may be done by any surfacing apparatus, and is done after the bifocal side has been formed, as above set forth, and after the large lens, shown in Figs. 5 to 9, has been cut to eye 'glass. size. That has the effect of changing the optical centers of the two bifocal surfaces from the center of the small lens surface. The optical center of the reading portion is thus moved to a point between the edge thereof and the line of joinder between the two surfaces and the o )tical center of the distance portion may fal within the distance portion of the lens, and this renders the lens comfortable and satisfactory to the eyes.

In the large lens having one visual surface surrounding the other, as shown in the first lenses illustrated in Figs. 5, 6, 7, 8 and 9, the inner surface, which is smaller than the surrounding surface, has a greater-positive focal power than such surrounding surface, so that when the lens is completed, as above explained, the smaller and previously central surface becomes the lower and reading surface of the lens, while the larger and previously surrounding surface will become the upper and distant surface of the finished lens, and said smaller and lower portion of the finished lens is optically stronger than the larger and upper portion of the lens.

The invention claimed is:

1. The process of makin a. bifocal lens from one piece of glass, inc uding as a step therein the simultaneous generation of two concentric spherically disposed visual surfaces of different dioptrics upon one face of the piece of glass.

2. The process of making a bifocal lens from one piece of glass, which process consists in first grinding two concentric spherically-disposed visual surfaces of different dioptrics upon one face of the piece of glass, so that the glass will be smooth and even and have a uniform thickness at the line of junction of said visual surfaces, second, in removing a portion of said piece of glass to give the remainder the form of a finished 7 lens and so that the inner visual surface will lie-near one edge of the finished lens, and third, in forming the other face of said piece of glass with the desired conformation.

In witness whereof I have hereunto set my hand at the city of 'Wilmington, count of New Hanover, and State of North Caro ina, this 17th day of April, 1919.

. D11. CHARLES W. CONNER.' 

